Math Problem Statement

Questions 1 to 22 carry 3 marks each.

7 A contractor hired a group of workers to do a job in 3 days. But due to poor work conditions, 8 workers dropped out every day, and hence the job could be completed only at the end of the 5th day. Initially how many workers were hired by the contractor?

  1. 45

  2. 40

  3. 48

  4. 36

Solution

Let the initial number of workers hired by the contractor be xx.

The job was supposed to be completed in 3 days. Therefore, the total work is equivalent to 3x3x worker-days (i.e., the total amount of work that needs to be done is 3×x3 \times x workers working for 3 days).

However, because 8 workers dropped out each day, the job was completed in 5 days instead. Let's calculate the number of workers available each day:

  • On Day 1, there are xx workers.
  • On Day 2, 8 workers dropped out, so there are x8x - 8 workers.
  • On Day 3, 8 more workers dropped out, so there are x16x - 16 workers.
  • On Day 4, 8 more workers dropped out, so there are x24x - 24 workers.
  • On Day 5, 8 more workers dropped out, so there are x32x - 32 workers.

The total work done over the 5 days can be calculated as the sum of the number of workers each day:

Total work=x+(x8)+(x16)+(x24)+(x32)\text{Total work} = x + (x - 8) + (x - 16) + (x - 24) + (x - 32)

Simplifying this expression:

Total work=5x(8+16+24+32)\text{Total work} = 5x - (8 + 16 + 24 + 32) Total work=5x80\text{Total work} = 5x - 80

Since the total amount of work is the same, we equate this to the original work, 3x3x:

5x80=3x5x - 80 = 3x

Solving for xx:

5x3x=805x - 3x = 80 2x=802x = 80 x=40x = 40

Thus, the initial number of workers hired by the contractor is 40\boxed{40}.

Would you like more details or have any questions?
Here are some related questions for practice:

  1. If 10 workers dropped out every day, how many workers were initially hired?
  2. What if the job was supposed to be done in 4 days but took 6 days instead?
  3. If the job took 7 days due to 5 workers dropping out daily, how many were initially hired?
  4. How does increasing the daily dropout rate affect the total number of days?
  5. Can you express the total work in terms of nn, where nn is the number of days the job took?

Tip: Breaking down word problems into smaller steps helps simplify the solution.

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Math Problem Analysis

Mathematical Concepts

Algebra
Linear Equations
Word Problems

Formulas

Total work = number of workers * number of days
Summation of workers available each day: x + (x - 8) + (x - 16) + (x - 24) + (x - 32)

Theorems

Basic principles of work and time (Work = Workers × Time)

Suitable Grade Level

Grades 9-11